Excavator buckets are used as accessory equipment for earth moving machines. Today, a variety of bucket configurations for different applications is available on the market. The bucket shape usually resides from the hydraulic excavator kinematics. Current developments and improvements of excavator buckets are regularly directed to an increase of the daily production in terms of the amount of material moved or to the reduction of wear of the bucket material. However, developments regarding the volume/weight ratio of the bucket have not been promoted as necessary in the past.
The inventors herein have recognized the above issues and therefore have aim to provide a solution for an excavator bucket which increases the volume/weight ratio.
The aforementioned object is solved by an excavator bucket for an earth moving machine, in particular a mining machine, comprising an interior bucket space for grabbing material to be moved. The interior bucket space is formed by a curved rear wall and a pair of opposed sidewalls.
The bucket according to the present disclosure is constructed in a box-type manner. A bucket box is arranged on the top surface of the bucket in a bucket area which comprises attachment devices for attaching the bucket to an excavator arm.
The bucket box is arranged at the rear wall, in particular arranged on the outer surface of its top portion. Further, the bucket box extends along a lateral axis of the bucket. According to the present disclosure the weight of the bucket, in particular the weight of the used bucket box is reduced if the angle between at least one bucket box front wall and the rear wall of the bucket, in particular its top portion, is less than 90 degrees. Consequently, the resulting bucket box comprises two front sides or rather outer lateral sides which are inclined to a vertical axis. The total material for manufacturing the bucket is significantly decreased although the resulting bucket volume remains constant.
According to a preferred aspect of the present disclosure the ratio between the bucket volume and its weight can be increased by a bucket construction with an angle between at least one sidewall and the curved rear wall which is greater than 90 degrees. Hereby, the bucket capacity can be appreciable increased. Further, only a very low weight increase has to be accepted. With a given bucket lip width the bucket width can be increased on a sidewall level so that the bucket volume increases.
The angle between at least one sidewall and the rear wall is not necessarily constant over the complete contacting area. It might be sufficient if some parts of the contacting area of side wall and rear wall draw an angle greater than 90 degrees.
In a preferable aspect of the present disclosure the curved rear wall is separated into a top portion and a base portion, wherein the sidewalls are located between the top and base portion. According to the preferred aspect the angle between at least one sidewall and the top portion and/or the base portion is greater than 90 degrees. The angle between at least one sidewall and the top portion and/or base portion is not necessarily constant over the complete contacting area. However, best effort is achieved with an angle between the top portion and the sidewall and with an angle between the base portion and at least one sidewall which are both greater than 90 degrees.
The best volume to weight ratio is achievable when both sidewalls are connected to the rear wall in an angle of more than 90 degrees.
It is possible to optimise the shape of the bucket box for further reduction of the overall weight of the bucket, in particular the weight of the bucket box. A good optimisation is achievable by accomplishing the bucket box as a hollow box wherein the longitudinal axis of the bucket box extends along the lateral axis of the bucket.
In particular, a bucket box comprises a four-corner cross-section area with rounded corners. Such a cross shape will show good properties with respect to its own weight. Ideally the four-corner cross-section area has rounded corners wherein the sides of the cross-section area differ from each other in their length and/or their orientation. Weight optimisation resists in the same way to the stresses generated by excavator work forces. Considering the aforementioned preferred modifications of the bucket box, a clear reduction of weight up to 30% compared to the weight of known boxes is possible. Both outer lateral sides may be inclined to a vertical axis, for example inclined to each other.
In a further preferred embodiment, the rear wall consists of at least two metal sheets which are brought together during manufacturing of the bucket to get a cambered and/or round shaped rear wall. These metal sheets are neither pressed nor molded. Instead, it is practical when the at least two metal sheets are indeed laminated, cut and welded together. Hereby, the bucket volume can be significantly increased without noticeable increase of the total weight of the bucket.
In a further preferred embodiment the top portion of the rear wall forms at least partly a circular shape. Former rear wall shapes may be rounded but usually include a straight portion forming the bucket top surface. According to a preferred embodiment of the present disclosure this portion is replaced by a top portion which forms at least partly a circular shape. The circular shape enlarges the available bucket volume.
For an improvement of the bucket lifetime it is very common to use wear packages. These wear packages are most of the time plates with a higher hardness face and which are welded on the bucket structure. According to a preferred embodiment of the present disclosure, instead, a carbide overlay is disposed at least partly on at least one defined structural bucket part which is intensely stressed.
It is very preferable when the aforementioned carbide overlay is disposed directly on the structural part after a cutting process of the bucket material and before a forming and welding process of the bucket material. The overlaying is feasible with a mechanical process.
Ideally, the used carbide overlay includes tungsten carbides which is very hard and can resist during the complete bucket lifetime. Therefore, it is possible to reduce the total bucket weight as the recharging is done directly on the bucket structure.
In an advantageous aspect of the present disclosure the bucket comprises at least one attachment flange for attaching the bucket to an excavator arm of an earth moving machine. It is possible that the bucket comprises at least two attachment flanges, each having one or more openings for a releasable connection of the bucket to an excavator arm of an earth moving machine.
It might be possible that at least one attachment flange is connected to the bucket box and/or the rear wall, in particular to its top portion.
The present disclosure is further directed to an earth moving machine comprising a bucket according to the present disclosure or according to any one of the preferred embodiments of the present disclosure. The earth moving machine may have hydraulic devices, such as hydraulic pumps, lines, accumulators, and control valves thereon for operating the attached bucket.
Obviously, the advantages and properties of the earth moving machine correspond to these of the inventive bucket. Therefore, a repeating description of the earth moving machine is deemed to be unnecessary.
Further properties and characteristics of the present disclosure should be explained in the following with respect to an embodiment given in the figures.